In patients with aortic stenosis routine preoperative hemodynamic assessment does not accurately predict long-term post-operative prognosis. Such assessments are performed with the patient at rest. Therefore, we used radionuclide cineangiography during exercise to assess left ventricular functional reserve capacity to determine accurately the functional status of the left ventricle, the relationship of ventricular function during exercise to prognosis and the effects of aortic valve replacement on left ventricular function.